THE AETIFICIAL PRODUCTION OF DIAMOND. 



73 



0'303-inch diameter had been drilled to a depth somewhat greater than the length 

 of the bullet, and in alignment with the bore of the gun ; the trigger was pulled by 

 a string from without. Cylindrical bullets of steel with a copper driving band were 

 used, shorter than the service bullet, and about one-half of the weight, some with 

 cupped noses to entrain material, some with coned noses to match the bottom of 

 the hole in the block. The velocity with 90 per cent, excess charge was estimated to 

 be about 5000 ft./secs. 



The substance to be compressed was placed either at the bottom of the hole when 

 the coned-nose bullet was used, or over the mouth of the hole when the cupped-nose 



Mazzle of 

 oaoarifle 



-o-3O3"dia. 



Fig. 6. 



bullets were used. Some of the bullets were of mild steel, but those with cupped 

 noses were of tool steel. 



The substances placed in the hole are given in the Appendix, and included graphite, 

 sugar carbon, bisulphide of carbon, oils, &c., graphite and sodium nitrate, graphite 

 and fulminate of mercury, finely divided iron and fine carborundum, olivine and 

 graphite. After each shot (fig. 7) the bullet and surrounding steel were drilled out, 

 and the chips and entrained matter analysed. 



Several experiments were also made with a bridge of arc-light carbon just over the 

 hole, raised to the limit of incandescence by an electric current, and the shot fired 

 through into the hole at the moment the carbon commenced to vaporize, as observed 

 in a mirror from without. Also an arc between two carbons was arranged just over 



